TUBE: 7868 SOURCE FILE: sheets/049/7/7868.pdf MANUFACTURER: RCA (Radio Corporation of America, Electron Tube Division / Electronic Components and Devices, Harrison, N.J.) YEAR: 1961 (7-61) for first datasheet; 1966 (10-66) / 1965 (5-65) for second bundled datasheet PAGES: 11 (TWO RCA datasheets bundled: pages 1-7 = DATA dated 7-61; pages 8-11 = DATA dated 10-66/5-65) ===== PAGE 1 (RCA 7-61, DATA 1) ===== 7868 Power Pentode NOVAR TYPE — For High-Fidelity Audio-Amplifier Applications GENERAL DATA Electrical: Heater, for Unipotential Cathode: Voltage (AC or DC) ......... 6.3 ± 10% volts Current at 6.3 volts ....... 0.8 amp Direct Interelectrode Capacitances (Approx.)(a): Grid No.1 to plate ......... 0.15 µµf Grid No.1 to cathode & grid No.3, grid No.2, and heater ... 11 µµf Plate to cathode & grid No.3, grid No.2, and heater ....... 4.4 µµf Mechanical: Operating Position ......... Any Maximum Overall Length ..... 3.24" Maximum Seated Length ...... 2.86" Length, Base Seat to Bulb Top (Excluding tip) ... 2.30" ± 0.09" Diameter ................... 1.062" to 1.188" Bulb ....................... T9 Socket ..... Cinch Mfg. Corp. No.149 19 00 24, or equivalent Base ....... Small-Button Novar 9-Pin (JEDEC No.E9-75) Basing Designation for BOTTOM VIEW ... 9NZ Pin 1 - Grid No.2 Pin 6 - Grid No.1 Pin 2 - Grid No.1 Pin 7 - Grid No.2 Pin 3 - Cathode, Grid No.3 Pin 8 - LC / Internal Connection - Do Not Use Pin 4 - Heater Pin 9 - Plate Pin 5 - Heater AF POWER AMPLIFIER — Class A1 Maximum Ratings, Design-Maximum Values: PLATE VOLTAGE ................... 550 max. volts GRID-No.2 (SCREEN-GRID) VOLTAGE . 440 max. volts CATHODE CURRENT ................. 90 max. ma GRID-No.2 INPUT ................. 3.3(b) max. watts PLATE DISSIPATION ............... 19 max. watts PEAK HEATER-CATHODE VOLTAGE: Heater negative wrt cathode .... 200 max. volts Heater positive wrt cathode .... 200(c) max. volts BULB TEMPERATURE (At hottest point on bulb surface) ... 240 max. °C Typical Operation and Characteristics: Plate Voltage .............. 300 volts Grid-No.2 Voltage .......... 300 volts ===== PAGE 2 (RCA 7-61, DATA 1) ===== Grid-No.1 (Control-Grid) Voltage ... -10 volts Peak AF Grid-No.1 Voltage .......... 10 volts Zero-Signal Plate Current .......... 60 ma Max.-Signal Plate Current .......... 75 ma Zero-Signal Grid-No.2 Current ...... 8 ma Max.-Signal Grid-No.2 Current ...... 15 ma Plate Resistance (Approx.) ......... 29000 ohms Transconductance ................... 10200 µmhos Effective Load Resistance .......... 3000 ohms Total Harmonic Distortion .......... 13 % Max.-Signal Power Output ........... 11 watts Maximum-Circuit Values: Grid-No.1-Circuit Resistance: Fixed-bias 0.3 max. megohm; cathode-bias 1 max. megohm PUSH-PULL AF POWER AMPLIFIER — Class AB1 Maximum Ratings, Design-Maximum Values: PLATE VOLTAGE ......... 550 max. volts GRID-No.2 VOLTAGE ..... 440 max. volts CATHODE CURRENT ....... 90 max. ma GRID-No.2 INPUT ....... 3.3(b) max. watts PLATE DISSIPATION ..... 19 max. watts PEAK HEATER-CATHODE VOLTAGE: neg 200; pos 200(c) BULB TEMPERATURE ...... 240 max. °C Typical Operation (Values for 2 tubes): Fixed Bias Cathode Bias Plate Supply Voltage 300 350 400 450 450 450 volts Grid-No.2 Supply Voltage 300 350 350 350 400 400 volts Grid-No.1 Voltage -12.5 -15.5 -16 -16.5 -21 volts Cathode Resistor (common to both) 170 ohms Peak AF Grid-No.1-to-Grid-No.1 V 25 31 32 33 42 31 volts Zero-Signal Plate Current 74 72 64 60 40 86 ma Max.-Signal Plate Current 116 130 135 142 145 94 ma Zero-Signal Grid-No.2 Cur 10 9.5 8 7.2 5 10 ma Max.-Signal Grid-No.2 Cur 28 32 28 26 30 20 ma ===== PAGE 3 (RCA 7-61, DATA 2) ===== Effective Load Resistance (Plate to plate) 6600 6600 6600 6600 6600 10000 ohms Total Harmonic Distortion 5 2.5 2 2.5 5 2 % Max.-Signal Power Output 24 30 34 38 44 28 watts Maximum-Circuit Values: Grid-No.1-Circuit Resistance fixed-bias 0.3 megohm; cathode-bias 1 megohm PUSH-PULL AF POWER AMPLIFIER — Class AB1 (Grid No.2 of each tube connected to tap on plate winding of output transformer = ULTRA-LINEAR) Maximum Ratings, Design-Maximum Values: PLATE AND GRID-No.2 (SCREEN-GRID) SUPPLY VOLTAGE ... 440 max. volts DC CATHODE CURRENT ... 90 max. ma GRID-No.2 INPUT ...... 3.3(b) max. watts PLATE DISSIPATION .... 19 max. watts PEAK HEATER-CATHODE VOLTAGE: neg 200; pos 200(c) BULB TEMPERATURE ..... 240 max. °C Typical Operation (Values for 2 tubes): Fixed Bias Cathode Bias Plate Supply Voltage 400 425 volts Grid-No.2 Supply Voltage (d) (d) volts Grid-No.1 Voltage -20.5 (c) volts Cathode Resistor (common) — 185 ohms Peak AF Grid-No.1 Voltage 41 42 volts Zero-Signal Plate Current 60 88 ma Max.-Signal Plate Current 115 100 ma Zero-Signal Grid-No.2 Current 8 12 ma Max.-Signal Grid-No.2 Current 18 16 ma Effective Load Resistance (Plate to plate) 6600 6600 ohms Total Harmonic Distortion 2.5 3.5 % Max.-Signal Power Output 23 21 watts ===== PAGE 4 (RCA 7-61) ===== Footnotes: a) without external shield. b) Grid-No.2 input may reach 6 watts during peak levels of speech and music signals. c) The dc component must not exceed 100 volts. d) Obtained from taps on the primary winding of the output transformer. The taps are located on each side of the center-tap (B+) so as to supply 50 percent of the plate signal voltage to the grid No.2 of each output tube. OPERATING CONSIDERATIONS: The bulb becomes hot during operation. To insure adequate cooling, it is essential that free circulation of air be provided. Dimensional drawing: T9, 3.24" max overall, 2.86" max seated, 2.30"±0.09", 1.188"max/1.062"min dia. Base JEDEC No.E9-75. (92CS-11061) ===== PAGE 5 (RCA 7-61) ===== AVERAGE PLATE CHARACTERISTICS (Ef=6.3 volts, Grid-No.1 volts=0, family of Ec2 100-400V) [courbes seules — pas de données tabulaires] (92CM-11074) ===== PAGE 6 (RCA 7-61) ===== AVERAGE CHARACTERISTICS (Ef=6.3 volts, Grid-No.2 volts=300, family of Ec1) [courbes seules — pas de données tabulaires] (92CM-11075) ===== PAGE 7 (RCA 7-61) ===== OPERATION CHARACTERISTICS Push-Pull Class AB1 (Ef=6.3V, Plate volts=400, Grid-No.2 volts=350, Grid-No.1=-16, Esig RMS=22.4) Power output & distortion vs load resistance [courbes seules — pas de données tabulaires] (92CS-11077) ===== PAGE 8 (RCA 10-66, DATA 1 — SECOND BUNDLED DATASHEET) ===== 7868 Power Pentode NOVAR TYPE — For Output Stages of High Fidelity Audio-Amplifiers and Radio Receivers ELECTRICAL Heater Characteristics and Ratings: Voltage (AC or DC) ......... 6.3 ± 0.6 volts Current at heater volts = 6.3 ... 0.800 amp Maximum Heater-Cathode Voltage: Heater negative wrt cathode .... 200 volts Heater positive wrt cathode: Peak 200 volts; DC component 100 volts Direct Interelectrode Capacitances (Approx.)(a): Grid No.1 to plate ......... 0.15 pf Input: G1 to (K+G3,G2,H) ... 11.0 pf Output: P to (K+G3,G2,H) ... 4.4 pf MECHANICAL Operating Position ......... Any Type of Cathode ............ Coated Unipotential Maximum Overall Length ..... 3.110" Maximum Seated Length ...... 2.750" Diameter ................... 1.062" to 1.188" Bulb ....................... T9 Bases (Alternates): Small-Button Novar 9-Pin (JEDEC No.E9-75); Small-Button Novar 9-Pin with Exhaust Tip (JEDEC No.E9-89) BASING DESIGNATION (Bottom View) 9RM Pin 1 - Grid No.2 Pin 6 - Grid No.1 Pin 2 - Grid No.1 Pin 7 - Grid No.2 Pin 3 - Cathode, Grid No.3 Pin 8 - LC (see Note) Pin 4 - Heater Pin 9 - Plate Pin 5 - Heater Note: May be used as tie point for components operating at or near the DC voltage of either the grid No.2 or plate, or between these voltages. Otherwise, do not use. AF POWER AMPLIFIER — Class A1 Maximum Ratings, Design-Maximum Values: PLATE VOLTAGE ......... 550 volts GRID-No.2 (Screen-Grid) Voltage ... 440 volts CATHODE CURRENT ....... 90 ma GRID-No.2 INPUT ....... 3.3(b) watts PLATE DISSIPATION ..... 19 watts BULB TEMPERATURE ...... 240 (* indicates a change) ===== PAGE 9 (RCA 10-66, DATA 1) ===== Typical Operation and Characteristics: Plate Voltage .............. 300 volts Grid-No.2 Voltage .......... 300 volts Grid-No.1 (Control-Grid) Voltage ... -10 volts Peak AF Grid-No.1 Voltage .. 10 volts Zero-Signal Plate Current .. 60 ma Max.-Signal Plate Current .. 75 ma Zero-Signal Grid-No.2 Current 8 ma Max.-Signal Grid-No.2 Current 15 ma Plate Resistance (Approx.) . 29000 ohms Transconductance ........... 10200 µmhos Effective Load Resistance .. 3000 ohms Total Harmonic Distortion .. 13 % Max.-Signal Power Output ... 11 watts PUSH-PULL AF POWER AMPLIFIER — Class AB1 Maximum Ratings: Plate 550; Grid-No.2 440; Cathode Current 90 ma; Grid-No.2 Input 3.3(b); Plate Dissipation 19; Bulb Temp 240 Typical Operation (Values for 2 tubes): Fixed Bias Cathode Bias Plate Supply Voltage 300 350 400 450 450 450 volts Grid-No.2 Supply Voltage 300 350 350 350 400 400 volts Grid-No.1 Voltage -12.5 -15.5 -16 -16.5 -21 (c) volts Cathode Resistor (common) 170 ohms Peak AF Grid-No.1-to-Grid-No.1 V 25 31 32 33 42 31 volts Zero-Signal Plate Current 74 72 64 60 40 86 ma Max.-Signal Plate Current 116 130 135 142 145 94 ma Zero-Signal Grid-No.2 Cur 10 9.5 8 7.2 5 10 ma Max.-Signal Grid-No.2 Cur 28 32 28 26 30 20 ma ===== PAGE 10 (RCA 10-66/5-65, DATA 2) ===== Fixed Bias Cathode Bias Effective Load Resistance (Plate to plate) 6600 6600 6600 6600 6600 10000 ohms Total Harmonic Distortion 5 2.5 2 2.5 5 2 % Max.-Signal Power Output 24 30 34 38 44 28 watts PUSH-PULL AF POWER AMPLIFIER — Class AB1 (Grid No.2 of each tube connected to tap on plate winding of output transformer = ULTRA-LINEAR) Maximum Ratings: Plate and Grid-No.2 Supply Voltage 440; DC Cathode Current 90; Grid-No.2 Input 3.3(b); Plate Dissipation 19; Bulb Temp 240 Typical Operation (Values for 2 tubes): Fixed Bias Cathode Bias Plate Supply Voltage 400 425 volts Grid-No.2 Supply Voltage (d) (d) volts Grid-No.1 Voltage -20.5 (c) volts Cathode Resistor (common) — 185 ohms Peak AF Grid-No.1 Voltage 41 42 volts Zero-Signal Plate Current 60 88 ma Max.-Signal Plate Current 115 100 ma Zero-Signal Grid-No.2 Current 8 12 ma Max.-Signal Grid-No.2 Current 18 16 ma Effective Load Resistance (Plate to plate) 6600 6600 ohms Total Harmonic Distortion 2.5 3.5 % Max.-Signal Power Output 23 21 watts ===== PAGE 11 (RCA 10-66/5-65) ===== Footnotes: a) without external shield. b) Grid-No.2 input may reach 6 watts during peak levels of speech and music signals. c) Connected to negative end of cathode resistor. d) Obtained from taps on the primary winding of the output transformer. The taps are located on each side of the center-tap (B+) so as to supply 50 percent of the plate signal voltage to the grid No.2 of each output tube. OPERATION CHARACTERISTICS Push-Pull Class AB1 (Ef=6.3V, Plate volts=400, Grid-No.2 volts=350, Grid-No.1=-16, Esig RMS=22.4) [courbes seules — pas de données tabulaires] (92CS-11077)